Size control of linear bodies



Nov. 17, 1953 L. c. ARGYLE 2,659,132

SIZE CONTROL OF LINEAR BODIES I Filed Oct. 25, 1947 4 Sheets-$heet l Nov. 17, 1953 c. ARGYLE 2,659,132

SIZE CONTROL OF LINEAR BODIES Filed Oct. 25. 1947 4 Sheets-Sheet 2 Nov. 17, 1953 L. c. ARGYLE SIZE CONTROL OF LINEAR BODIES 4 Sheets-Sheet 5 Filed Oct. 23. 194? ALLA 'vvvY 511mb: [sear C. ARGYLE Nov. 17, 1953 L. c. ARGYLE 8 SIZE CONTROL OF LINEAR BODIES Filed Oct. 25, 1947 4 Sheets-Sheet 4 IO4- I I I I43 I46 inventor Z EROY C ARGYLE Patented Nov. 17, 1953 SIZE CONTROL OF LINEAR BODIES Leroy C. Argyle, Elmira, N. Y., assignor to Corning Glass Works, Corning, N. Y., a corporation of New York Application October 23, 1947, Serial No. 781,575

7 Claims.

The present invention relates to the continuous production of linear bodies of thermoplastic material, and has for its object attainment of greater uniformity in thickness of suchbodies than realized by former methods. By way of example, the invention is herein applied to the continuous production of glass tubing from a molten supply body in known manner; for example, by a structure such as shown in Patent 2,085,245 granted to William J. Woods June 29, 1937, wherein the tubing is drawn upward from a molten supply body and compressed air supplied to the bore thereof as required to maintain a desired cross-sectional diameter.

In accordance with the invention, the tubing is gauged near the source of the draw, and in response to thickness variations still well within acceptable tolerances, the gauging device initiates changes in the volume of air supplied in small increments until the tubing is of a thickness with in a predetermined narrower range of tolerances. It is recognized that in the continuous production of tubing, from time to time foreign bodies enter the stream and when a section of the tubing containing such a body passes the gauging device, a momentary indication will be given of a needed corrective adjustment. Corrective adjustments under these circumstances are, however, prevented by a timing device which delays the initiation of corrective adjustments until the need for a corrective adjustment has persisted for a predetermined time interval.

In the accompanying drawings Fig. 1 is a plan view of a gauging apparatus embodying the invention, with part of the supporting means therefor shown in section and showing a section of tubing between its gauging rollers.

Fig. 2 is a side elevation of the gauging appa ratus showing the overhead support therefor. The figure also shows a section of tubing between the gauging rollers.

Fig. 3 is an enlarged sectional View taken on line 3-3 of Fig. 1.

Fig. 4 is an enlarged sectional view taken on line 44 of Fig. 1.

The left portion of Fig. 5 shows in sectional elevation a fragment of the tube-drawing apparatus disclosed in the cited Woods patent, having associated therewith tubing drawn from such apparatus and the gauging apparatus shown in detail in Figs. 1-4.

The right portion of Fig. 5, together with Fig. 6, illustrate circuits under the control of the gauging apparatus and a motor-driven air supply valve 2 for the drawing apparatus under the control-of such circuits.

Fig. 7 illustrates an alternative arrangement for supplying air to the bore of the tubing being drawn.

Gauging apparatus Referring now to the drawings in detail, and particularly to Figs. 1-4., the gauging apparatus comprises rollers I I and I2 carried on axle shafts I3 and I4. The shaft I3 is mounted in ball bearing assemblies I5 and I5 (Fig. 3), carried in a suitable housing I6 having a depending switch supporting bracket II. Arranged on the underside of housing I6 and extending in a horizontal plane transverse to axle I3, is a bar I8 having an inverted V-groove I9. Facing V-groove I9 is a V-groove 2D in the upperside of a supporting track 2| suspended from suitable hangers 22 and 23, as illustrated in Fig. 2. The unitary structure comprising housing I6 and switch support I! is supported on ball bearings 24 and 24' arranged in the space between V-grooves I9 and, 20, so that the housing I6 is freely movable along the length of support 2I. To prevent possible swinging movement of the housing I5 out of a horizontal plane, support I! is provided with a key 25 (Fig. 3) having an extension 26 occupying a groove 21 in the bottom of support 2!. Pivotally mounted on the side of depending portion I! opposite support 2| are switch arms 3I-34 suitably insulated from one another and each having a break contact normally engaging a similar contact carried by a suitable support (Figs. 2 and 5). g

The axle shaft I4 (Figs. 1 and 4) is mounted in the same manner as is shaft I3 in a similar housing 42 having a depending micrometer support 43, held against swinging movement by a key 45 having an extension 46 occupying groove 21. The structure comprising parts 42 and 43 is also mounted for free movement over support 2 I in the same manner as is the structure comprising parts I6 and H. The support 43 has mounted thereon micrometers 5|54 (Figs. 2 and 4) arranged in operative relation with switch members 3I3i, and so adjusted that when tubing below a predetermined maximum diameter passes between rollers II and I2, the micrometer 54 will engage switch member34 and break a circuit between it and the associated contact carried by member 40. Micrometers 53, 52 and 5I are adjusted to operate the switches associated with them as tubing of progressively smaller diameters passes between rollers II and I2, as will be more fully brought out hereinafter. The means for maintaining the rollers I I and I2 in engagement with the tubing, irrespective of its size, comprises a Y-toggle 55 and a cooperative weight 55, as illustrated in Fig. 5.

Drawing apparatus The drawing apparatus as illustrated comprises a refractory bowl 90 containing molten supply body of glass 9 I, from the upper surface of which tubing 92 is drawn by suitable tractor rolls and 94. The tube diameter is controlled by supplying positive air pressure to its bore from a supply pipe 95 to which air is supplied from a line 91 under control of a motor actuated valve 95, illustrated in Fig. 6.

Indicating equipment Equipment is provided for indicating whether the tubing being drawn is within an ideal tolerance range, is acceptable but smaller than ideal, is acceptable but larger than ideal, is too small, or is too large. Clocks are also provided for measuring time periods during which the tubing is either too large or too small.

The control of this equipment is by means of a group of relays RI-R4 in turn under control of the gauging apparatus. Relay RI, for example, is maintained energized over a circuit extending from the conductor I08 of a 1l0-volt alternating current supply source, conductor I01, conductor I06, the winding of relay RI, and the plate of an amplifier tube AI. The relay is energized during the positive half-cycle charges received over this circuit and is held energized during the negative half cycle by a charge stored in the associated condenser I0. Positive charges are supplied to the relay RI so long as the grid of tube AI remains connected to the line L leading from a transformer TI. This circuit extends through the member 40, switch arm 3|, and line LI to the grid of the tube. Similar circuits for maintaining relays R2R4 energized include branches extending through the switch arms 32-34, lines L2L4 and the grids of amplifier tubes A2-A4. The micrometers 5I-54 are so adjusted that when the tubing passing between gauging rollers II and I2 is too large, all of the relays RIR4 will be energized. When the tubing is oversize but acceptable, micrometer 54 will actuate the switch arm 34 to open the circuit to the grid of tube A4 and thereby brin about the de-energization of relay R4. As progressively smaller sizes of tubing pass between rollers I I and I2, micrometers 53-5I will open the circuits to the grids of tubes A3-AI to effect the successive de-energization of relays R3 RI.

With relays RIR4 all energized, a circuit extends from conductor I00 through conductors I02, I03, a lamp L, conductors I04 and I05, the contacts of relay R3, conductors I 06, I01, to the conductor I08, so that lamp L lights up and indicates that the tubing being drawn is too large. At the same time a circuit is established over conductors I01, I06, the front contact on relay R4, conductor II2, through the clock III to conductor I I 0, and through conductors I03, I02, to conductor I00, so that this clock times the period during which the tubing being gauged is too large.

When the tubing being gauged is larger than ideal but acceptable, relay R4 is de-energized, at its front contact breaks the traced circuit for the clock I I I, and at its back contact establishes a circuit over conductor 2' through the front contact of relay RI and an O. K. lamp to conductor I03, so that the O. K. lamp and the lamp L iii.

are both lighted to indicate that although the tubing is larger than ideal, it is of a size which is acceptable.

When the tubing being drawn is in the ideal size range, micrometer 53 is enabled to actuate switch arm 33 to break the circuit to the grid of tube A3 so that relay R3 becomes de-energized and thus opens the traced circuit for lamp L, so that only the O. K. lamp is lighted, thus indicating that the tubing is of the ideal size.

When the tubing being drawn is acceptable but under the ideal size range, the micrometer 52 is enabled to actuate the switch arm 32 to interrupt the circuit to the grid of tube A2, so that the relay R2 becomes tie-energized and at its contacts completes an obvious circuit for the lamp S. When this lamp is lighted in conjunction with the O. K. lamp it is an indication that the tubing being drawn, although smaller than ideal, is of an acceptable size.

When the tubing being gauged is soo small, the micrometer 5! is enabled to actuate switch arm BI so that relay RI will become ole-energized to, at its front contact, open the circuit of the O. K. lamp and at its back contact close a circuit for the clock I2I via conductor I I2 and the back contact of relay R4, so that this clock measures the time during which the tubing being drawn is too small for use. Lamp S is lighted over the obvious circuit including the contacts of relay R2, thus indicating that the tubing being drawn is too small.

Size control As previously mentioned, the control of the size of the tubing is determined by the amount of air supplied to its bore by valve 96. This valve is adapted to be operated by a shaded pole motor M which operates in one direction when one pair of its shading coils is shunted, and in the other direction when the remaining pair of its shading coils is shunted. The motor may also be operated to increase or decrease the air supply by manual actuation of push button I25 or I26. When button I25 is depressed a shunt circuit about shadin ooils I50 and I5! is established through conductor I3I, the make contacts of push button I 25 and conductor I33, whereupon the motor will operate in the proper direction to increase the air supply to pipe 95. By pressing push button I26, shading coils I52 and I53 are shunted over a circuit including conductor I3I, the break contacts of push button I25, the make contacts of push button I 25 and conductor I32. The push button control is provided, however, primarily to enable large corrective changes to be made, as may be required when changing from the drawing of one size range of tubing to another. As heretofore stated, the invention provides for automatically making corrective changes while the tubing being drawn is still within an acceptable size range.

Before describing the automatic regulating operations the timing device used in connection therewith will first be described. This device operates on the principle of a capacitor to a predetermined voltage and then discharging the same through a high resistance until the voltage of the grid of a vacuum tube connected to the capacitor drops to a point where the tube will conduct suflicient current to energize an associated relay. The timers as shown comprise vacuum tubes VII and VTP. and associated circuits. The timer VTI is employed to delay an actual corrective change being made until the gauging apparatus has, for a predetermined time, passed tubing outside the ideal size range. The timing device employing tube VT2 serves the function of breaking up the corrective change into small increments. Since these timers are alike, a description of one will suflice. While the tubing being gauged is of ideal size, the grid bias capacitor MI is precharged through grid rectification because the cathode is connected through resistance I46 to the same line; namely, line I06, as the anode, so that there can be no electron flow from the cathode to the anode. However, the grid is connected through capacitor MI and resistance I42 to a preset point I45 of the potentiometer I44 which in series with a resistor I43 extends between the lines I and IE6 of the A. C. source. Thus grid current will flow charging condenser I4I to almost the full peak difierence in potential between the preset point I45 of the potentiometer and the line Hill. This is because the resistance I46 is such that it represents but a small percentage of the resistance I42 that the voltage drop in resistance I46 may be included;

The timing operation is initiated by connecting the cathode of VTI to the line conductor I90 which is via conductor I39, the contacts of relay R1, the lower contacts of relay R and conductor IIJ3 or, alternatively, the lower contacts of relay R5. When this is done the cathode grid potential consists of negative direct-current voltage stored in condenser I4I superimposed on an inphase alternating-current voltage consisting of that portion of the voltage across the potentiometer between the preset point I45 and line I00. The time delay is determined by the decay of the voltage across capacitor I4! as it discharges through the resistance I42. Since these components are of fixed value, the time constant or cycle is fixed and the time is determined by the point at which the grid circuit is connected to the potentiometer so that the time delay may be varied by merely changing the set point I45.

The automatic corrective regulation of air supply is under the control of relays R5 and RE. Relay R.5 is connected to conductors I03 and I28 in multiple with lamp S, and accordingly becomes energized whenever the lamp S is lighted to indicate that the size of tubing being drawn is below that desired. Thus, in the manner previously described in conjunction with the operation of lamp S, the relay R5 is energized by operation of the gauging apparatus when the size of the tubing is below that desired. Belay R5, upon operating, at its upper make contacts, closes a point or circuit member in an operating circuit for motor M, namely a shunt circuit about shading coils I50 and I5I and at its lower make contacts completes the previously traced circuit from the conductor I00 through conductors I02, I03, contacts of relay R5, and the break contacts of relay R1 and conductor I39 to the cathode of tube VTI, so that in the manner already described, the timing operation is initiated. If this circuit remains completed until condenser I4I has been wholly discharged that is, until completion of the predetermined cycle of the timer. then, relay R8 becomes operated and closes its middle contacts which constitute a second member in the prepared shunt circuit about the shading coil windings I50 and HH This closure completes the motor operating circuit thus initiating operation of motor M which, in turn, operates the air controlled device, valve 96. This circuit extends from conductor I3I through break contacts of push buttons I25 and I26, conductor I48, the middle contacts of relay R8, the upper contacts of relay R5 to conductor I33. The motor M accordingly operates in the proper direction to increase the supply of air to pipe 95. Relay R8 also at its outer contacts closes a circuit through a lamp V0, which becomes lighted to indicate that the motor M is operating. Finally, relay R8 at its innermost contacts connects the cathode of tube VT2 directly to conductor I00 so that the condenser I62 starts discharging to measure the time of operation of motor M. When this time has expired, relay R1 becomes energized and breaks the previously traced circuit to the oathode of tube VTI. Accordingly, relay R8 is immediately restored, and whether or not a further corrective change is made, is made dependent on whether relay R5 continues to remain energized for the time required to again efiect the energization of relay R8.

The relay R3 is in bridge of conductors I03 and IE4 in multiple with lamp L, and accordingly, Whenever the tubing being drawn is larger than ideal, relay R6 operates to initiate the same cycle of operations initiated by the operation of relay R5, except that relay R6 at its upper contacts completes a shunt about windings I52 and I53 of the shading coils so that if the motor is operated, it operates in a direction to decrease the amount of air supplied to pipe 95.

In the drawing of some sizes of tubing it may be found that one operating increment of valve makes an over correction beyond the adjustable time range of the timer VT2. Under such conditions the modified arrangement illustrated in Fig. 7 may be employed. By supplying the greater percentage of air required through a by-pass valve 98, the sensitivity of control exercised by valve 96 can be reduced to meet the most critical needs.

From the foregoing it will be appreciated that the equipment under control of gauging rollers I I and I2 is adapted to control the air supply to the tubing in such a precise manner that most corrective changes are made before the tubing attains a size outside the acceptable tolerances. It should be further understood that although the invention has been herein shown as applied to the drawing of a tubular body of material and varies the applied air pressure to exercise the regulation of the tubing size, the invention is equally adaptable to the drawing of a linear body of solid material. such as, for example, glass cane. Under these circumstances the motor M would be employed to actuate a rheostat in circuit with the motor employed to drive the tractor rolls 93 and 94 so that size control would be regulated by rate of draw rather than by change in air pressure.

The foregoing control apparatus may also be employed either alone or in combination with one or both of the foregoing arrangements to regulate the heat applied to the molten supply body, or to regulate the application of a heating or cooling medium to the material issuing from such body to regulate its viscosity as required to maintain a desired thickness range of the final product without departing from the spirit and scope of the invention.

What is claimed is:

1. In the method of continuously producing a linear body of material of a desired thickness range, the steps of passing the body through a gauging device for measuring the thickness of the body, said gauging device being positioned near the source of formation of the body and operatively connected to a timing device having a fixed predetermined cycle, initiating the operation of the timing device by operation of the gauging device when the thickness of the body is outside of the desired range and initiating a size correction of the body only after the timing device has completed its predetermined cycle and only when said thickness of the body as measured by said gauging device continues to be outside said desired range throughout said predetermined cycle.

2. A method such as defined by claim 1 wherein the linear body is composed of thermoplastic tubing issuing from a source of formation and maintained at a desired minimum size by air continuously supplied at a constant rate and size regulation is effected by variation of the volume of air via an auxiliary path.

3. For use with a thermoplastic tube-drawing machine wherein air is supplied to the tubing during the draw, a gauge through which the drawn tubing is passed, a timing device having a fixed predetermined cycle and operatively connected to the gauge, the operation of said timing device being initiated by operation of the gauge when the size of the tubing is outside of a desired range, an air control device adapted to increase the amount of air supplied when the tubing being gauged is below a predetermined minimum value and to decrease the amount of air supplied when the tubing being gauged is above a predetermined value, and means jointly controlled by said gauge and said timing device for initiating operation of said air control device only after the timing device has completed its predetermined cycle and only when said size of the tubing as measured by said gauging device continues to be outside the desired range throughout said predetermined cycle.

4. For use with a machine for continuous drawing of glass tubing from a supply body of molten glass and employing a source of compressed air supplied to the tubing to maintain a desired tube diameter, an air supply valve having an associated reversible motor operable to open and close said valve to regulate the diameter of the tubing being drawn, actuating circuits for said motor, separate relays having contacts included in said circuits, a third relay having contacts included in said actuating circuits, a timing device under control of each of said separate relays adapted to effect the energization of said third relay to complete an operating circuit for said motor after a predetermined time interval providing one of said separate relays is at the time also energized, and means including a gauge cooperative with the tubing being drawn for selectively effecting the energization of said separate relays as the tubing diameter varies beyond predetermined tolerances.

5. In an arrangement such as defined by claim 4, a second timing device having an operating circuit closed by said third relay on its energization, and a fourth relay operated by said second timing device at the expiration of a predetermined period having contacts-included in the operating circuit of said first timing device so that said first timing device is disabled to disable the operating circuit for said motor after a predetermined time delay.

6. For use with equipment for the continuous fabrication of a linear body of material, an associated thickness gauging device through which the body passes, a timing device having a fixed predetermined cycle and operatively connected to the gauging device, the operation of said timing device being initiated by operation of the gauging device when the thickness of the body is outside of a desired range, mechanism for applying corrective adjustment to said equipment in small increments, and an operating circuit for said corrective mechanism including a circuit member closed only during passage through said gauging device of material outside the desired thickness range and a second circuit member closed only by the completion of said predetermined cycle of the timing device, effective operation of the corrective mechanism thereby being initiated only after the material passing through the gauging device continues to be outside the desired thickness range throughout said predetermined cycle of the timing device.

7. A gauging arrangement comprising a pair of gauging elements, independently movable supports for said elements, means tending to move said supports toward one another to bring said elements into continuous engagement with opposite sides of a linear body of material issuing from a source of fabrication thereof being passed therebetween, electrical circuit switching contacts associated with one of said supports, actuators for said contacts associated with the other of said supports and set to actuate a number of said contacts depending on the thickness of the body being passed between said elements, and means under control of certain of said contacts for modifying conditions at the source of fabrication to correctively change the thickness of the body being produced each time certain of said contacts remain actuated for a predetermined time period.

LEROY C. ARGYLE.

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